Promising New Treatment for the Deadly Ebola Virus

Current treatments for the Ebola virus only work when they are given immediately after infection. A recent study published in Science Translational Medicine describes a new antibody cocktail that was effective in macaques up to four days after infection. Lead author Gary Kobinger discusses how the treatment targets the virus's quick replication process.

JOHN DANKOSKY, HOST:

Now, for many of us, we first heard about the Ebola virus from the movie "Outbreak," Dustin Hoffman trying to contain an outbreak of an Ebola-like virus in a small California town. Well, in the 18 years since that movie came out, the Centers for Disease Control and Prevention has documented 18 known outbreaks of Ebola, with the most recent happening last fall in the Congo.

The virus causes internal and external bleeding, fever, and has a 90 percent fatality rate. It is a nasty, fast-acting virus and so far the only treatment out there only works if it is administered just minutes after infection. But there's a group of researchers one step closer to finding a treatment. Reporting in Science Translational Medicine, they say their cocktail is effective in macaques up to four days after the infection.

Gary Kobinger is the lead author in that study and chief of the Special Pathogen Program at the National Microbiology Laboratory in Winnipeg, Manitoba. Thank you so much for joining us.

GARY KOBINGER: Well, thank you for having me.

DANKOSKY: First of all, what exactly is Ebola and how is it spread?

KOBINGER: Ebola is a virus that is spread mainly through close contact with either anything that is infectious - it could be an animal, it could be another human that is sick, for example - and it's a virus that replicates in different organs. And the feature of that virus and why it makes it - it's so aggressive, or one of the reasons why it's so aggressive is that it's very, very fast.

As you just said, it's a very fast virus that replicates so fast that we don't have time to basically defend ourselves against it.

DANKOSKY: You say contact with animals. We've heard about fruit bats, maybe from pigs. What do we know about the animals that could be causing this?

KOBINGER: Well, there is - what causing this. So more and more, there's I think like agreement in the field that the bats are really the starting point. So the host, so to speak, of the virus. And then probably there is a different species that are involved in to - what we call amplifying host. And these host, these animals, they amplify the virus. They can amplify it to a level that is promoting transmission.

And some of these animals are, for example, (unintelligible) primates in the wild. And they also die of the disease and by - in that process, the virus reaches a very high level in the blood. So when a human get in contact with those infectious materials, there is documented cases of transmission, for example, between great apes and humans. And then humans to humans.

DANKOSKY: Explain where we would normally see Ebola outbreaks. What sorts of communities is it found in?

KOBINGER: Well, it's mainly in central Africa, you know, and often in very remote locations. And it's part of the challenge but it's also the reason why we don't hear so much about outbreaks of Ebola, aside from the fact that it is a very aggressive infection. They are mainly in central Africa.

DANKOSKY: You talk about the speed and how quickly it moves. Why exactly is this so difficult to treat? Why has it been so elusive to find a cure for this?

KOBINGER: Well, this is the reason, is that if you have only a few days where you have a window where you can intervene with treatments, it's very challenging because of - actually from a few days it could be only a few hours. And at one point, a virus can cause enough damage that it's what we call the point of no return. And it doesn't matter at that point what you can do. It's too late.

So that's why it's such a challenging virus to fight, basically, because the window is so short from exposure to death. There is only a few days. And won't last a few days. It's usually, you know, it can be anywhere from six to even more, 20 days, but it's frequent to see from exposure to death within 10 to 15 days, example.

And then the window is very short. If you have somebody that shows up with symptoms, you know, it's not - there is not a lot of time before it will get into point of no return.

DANKOSKY: So let's talk about in your study you describe this three-antibiotic cocktail. Describe what exactly this is and how you think it works.

KOBINGER: Right. So antibodies. We make them naturally every time, you know, if we have a normal immune response or immune system. When we get in contact with an infectious agent our immune system sees it as an invader and develop different kinds of responses. And one of them is antibodies.

And these antibodies, they can target the invader and try to, through a different mechanism, can control and kill even the invaders. And so what we did here is that we generated three different antibodies in the lab and these different antibodies, they are three little missiles, if you want.

And they will target the outer shell of the virus and they can attach to it. And we know at least that by doing so, they make entry into cells either impossible or extremely difficult. So the key here with the treatment was to keep the virus replication or the amount of virus very low in the host while the host is defending itself to buy time, if you want. And this is what we are doing with this treatment.

DANKOSKY: I'm John Dankosky and this is SCIENCE FRIDAY from NPR. Now, you've tried an antibody treatment before. What did you do differently this time around?

KOBINGER: Well, this time we combined it to another molecule that is being made naturally which is called interferon alpha. So the body also makes this in the natural way except that it takes time to be activated. By the time we get in contact with an infectious pathogen, an invader, it takes days before we produce this molecule.

And here what we did was we basically gave the molecule ready to go at the same time that we gave those antibodies or those three missiles. So at the same time we were attacking the virus we were stimulating and helping the host to fight back and to defend itself against the invader.

DANKOSKY: Now, you've tested this in macaques. How effective has the treatment been on them?

KOBINGER: Well, you know, it's been for us, you know, it's been a surprise, I have to say, because in the field there's been a question whether or not it will be possible ever to treat and save an animal that represent very closely the case of a human infection and to treat that animal once symptoms and once the virus can be detected in the blood.

Because once you get exposed, it takes a few days before you develop a fever, you develop different non-specific which I call flu-like symptoms. And once you're at that point you're already maybe three days, four days into the infection. You may have only three, four, five days before you die. So the point of no return is even before that.

So what's very surprising to us is - we were very optimistic but we were not thinking we would be able to rescue 100 percent of the animals, even at that later time point where basically it's only a few days before death.

DANKOSKY: Now, do you have human trials scheduled? Do you think this treatment could lead to a vaccine?

KOBINGER: Absolutely. It's a treatment that we are trying to move as fast as possible with very good scientists from the U.S. including USAMRIID, NIH, and a company called MyBio in California. And we are targeting late 2014, early 2015, provided we can get all the approval by then.

But we are quite optimistic. And it's a very optimistic schedule but I think we can make it happen. And for us it will be tremendously important because as we work with the virus every day, to have something like this, to be able to rely on will be fantastic.

DANKOSKY: Now, something we've been reading a lot about recently is that the U.S. government seems very interested in Ebola, worried perhaps that this could be used for bioterrorism. Is this something that the government should be concerned about?

KOBINGER: Well, you know, yes, they have shown interest, definitely, in the treatment. And there is, you know, it's public knowledge that there is a - the virus has been produced in a way that it could be weaponized. So you can imagine with a virus that can cause fatality rate of 90 percent, it can be seen definitely as an important threat.

So this is why the U.S. government and other governments have been putting Ebola on their top priority list to develop a countermeasure, a medical countermeasure, to make sure that, you know, we could be protected if ever we would need a treatment against this agent.

DANKOSKY: Gary Kobinger is chief of the Special Pathogen Program at the National Microbiology Laboratory in Winnipeg, Manitoba, Canada. Thank you so much for joining me. I appreciate it.

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